Johnny Manziel humbled himself on the eve of training camp Friday night and admitted he hasn't approached his offseason in the most professional manner.

"At the end of the day, I've made some rookie mistakes,'' he said after a conditioning session for most veterans Friday night. "There's some things that I wish I could've gone back and done a little differently, but I'm continuing to move forward and trying to represent this organization in a positive manner and a positive light, so just very excited to be back in camp and it's football 24/7 and that's what I love doing. That's what I live for and it's what my job, so for me, I'm very excited to be back and can't wait to get this underway.''

He said he doesn't think his partying ways in the offseason have set him back in his bid to unseat Brian Hoyer for the starting quarterback job. Sources told cleveland.com the club was alarmed by some of Manziel's offseason behavior, including a photo that showed him tightly rolling a $20 bill in the bathroom of a bar.

"I don't think (it's hurt me),'' he said. "I think there are definitely things I can do moving forward to better act as a professional and at the same time I'm still learning how to do that, still getting used to this role, still getting used to this league, still getting used to being a pro football player. I'm not in college anymore and there's just things I need to do better and that's just part of being a professional. Hopefully with time and going through this season and as time goes on, I'll get better at doing that.''

Manziel, who will start training camp with the second-team offense, acknowledged that he had a heart-to-heart talk with coach Mike Pettine and general manager Ray Farmer about his approach to his craft and what they expect. For the first time since he was drafted, he was contrite about his frat-boy romp from coast to coast. In fact, he addressed it in an opening statement before taking questions at the podium.